Switch mechanism for automatic stokers



p 7, 1948. G. w. CRISE SWITCH MECHANISM FOR AUTOMATIC STOKERS Filed Dec. 8, 1945 mvgsmox e W. Crzse Ge or ne: mm

Patented Sept. 7, 1948 UNITED STATES PATENT OFFICE SWITCH MECHANISM FOR AUTOMATIC STOKERS George W. Crise, Columbus, Ohio Application December 8, 1945, Serial No. 633,815

6 Claims. 1

My invention relates to temperature control switches of the type incorporating a timing mechanism in governing the operation thereof. More specifically, it relates to temperature control switches used for controlling automatically the operation of fuel stokers for furnaces.

In furnaces of this type, it is necessary that the stoker be driven at definite intervals so as to provide sustained combustion of fuel in the furnace. In relatively mild weather, it is a matter of common occurrence that the operative circuit controlling the motor employed in driving the blower and fuel-feeding auger of a standard stol-rer is not closed under the automatic control of the thermostatic switch at intervals of time spaced sufiiciently close to insure a sustained low-fire condition of operation.

To avoid this condition, it is an Object of my invention to provide a thermostatic switch whose operating circuit is closed at time-regulated intervals independent of thermostatic action, whereby to assure adequate combustion of the fuel.

Another object of my invention is to provide a time-regulated thermostatic switch whose operating life is greatly extended by the elimination of wearing parts within the time-driven mechanism.

For a further understanding of the invention, reference is to be had to the following description and the accompanying drawings, wherein:

Fig. 1 is a diagrammatic view disclosing my improved switch mechanism for temperaturecontrolling apparatus;

Fig. 2 is a side elevational view partly in vertical section of the chronometer switch;

Fig. 3 is a detailed vertical-sectional view taken along the line 3-3 of Fig. 1;

Fig. 4 is a perspective view of the two magnets contained in the chronometric switch.

Referring to Fig. 1 of the drawings, my temperature-control switch comprises a synchronous motor 5, speed reducing gears 6 driven by the motor 5, a rotating cam 1 connected with, and driven at a relatively slow speed by the gears 6, a thermostat 8 having normally spaced contacts I and In which upon engagement close an operating circuit, an adjustment arm II for the thermostat 8 actuated by the rotating cam I so as to vary the spacing between the contacts 9 and Ill independent of thermostatic action, and a chronometric switch I! electrically connected to the operating circuit of the thermostat 8 and serving by its action to close the operating circult independent of the thermostat 8.

Referring to Fig. 2 -of the drawings, the chronometric switch l2 comprises a base iii, a rotating gear ll, a magnet l5 radially mounted and movable on the rotating gear I4, a set screw l8 incorporating a time-calibrated scale and directly connected with the magnet l5, thereby serving to rotate the magnet 15 on the gear I! causing a circular displacement of its magnetic field, a second magnet H having a resilient supporting arm 68 and movable toward the magnet l5 when in registration therewith, and a pair of contact terminals l9 and lil, said terminal l5 being rigidly attached to the supporting arm I8 is adapted for engagement with the terminal 26 when the magnets i5 and H are in registration with each other.

In the operation of the chronometric switch H, the rotating gear I is driven at a given rate of speed, such as one revolution per hour, by the synchronous rotor 5. Thus, the magnet 65, attached to the rotating gear It, is brought in direct registration with the second magnet ii for a short period oi time during each revolution.

Referring to Fig. 4 of the drawing the magnets l5 and H are so situated, when in registration with each other, as to cause an attraction between the two. The magnet i5 is connected directly to the set screw 56 so that when the set screw 86 is rotated there is a circular displacement of the magnetic poles of magnet it,

thereby causing a varying degree of attraction between the magnets l5 and IT, resulting in a shortening or lengthening of the period of attraction between the two. When the magnets HQ and I1 are in registration with each other, the magnet l'l, having a resilient supporting arm I8, moves toward the magnet l5, thereby engaging the contact terminals I9 and 20 and closing the operating circuit of the switch.

Referring to Fig. 3 of the drawings, in operation the cam 1, comprising a node 2| and a dwell 22, is rotated at a relatively slow speed, such as one revolution per twenty-four hours, by the speed reducing gears 5. The adjustment arm H of the thermostat 8 is held by spring tension against the circumference of the cam 1, and is subject to circular displacement by the node 2! when the cam I is rotated. The displacement of the adjustment arm II in turn, causing a variance in the spacing of the contacts 9 and Ill independent of the action of the thermostat 8.

In view of the foregoing, it will be manifest that the present invention provides a time-regulated switch for opening and closing the operating circuit of an automatic coal-feeding stoker at definite intervals, and in a manner independently of the usual control for such a circuit atforded by the thermostatic switch. The construction is characterized by its structural simplicity, manufacturing economy and operational reliability. The switch functions automatically and requires but little or no manual attention after the same has been properly adjusted to meet operating conditions. It will be understood that the construction disclosed is exemplary of but one of the embodiments of the invention, therefore, the same is subject to certain modifications without departing from the scope of the following claims.

I claim:

1. In a mechanism of the character described, a time-operated switch comprisin a rotatable element driven by chronometric motor means, an adjustable magnet attached to said rotatable element and movable thereon so as to cause a circular displacement Of its magnetic field. a second magnet in spaced longitudinal relationship with the circumference of said rotatable element and having a resilient supporting body, and a pair of oppositely disposed contact terminals having an operating circuit, one of said contact terminals being rigidly attached to and movable with the resilient supporting body of the second magnet.

2. In a mechanism of the character described, a time-operated switch comprising a driven rotatable element having an adjustable magnet radially mounted thereon, a chronometric means for driving said element, a time-calibrated ad- ,iustment means mounted on said rotatable element in relation to said adjustable magnet so as to vary the displacement of its magnetic field, a second magnet in spaced longitudinal relationship with the circumference of said rotatable element and having a resilient supporting body, and a pair of oppositely disposed contact terminals, one of the latter being rigidly attached to and movable with the resilient supporting body of the second magnet.

3. In a timing switch, a movable primary magnet traversing a fixed path of travel, a second magnet positioned near said path of travel and changing the maximum mutual attraction between the elements, said means including s. rotatable mounting for adiustably turning one of the magnetic elements.

5. In a magnetically operated switch, a pair of normally spaced cooperative magnetic elements, a yieldably mounted contact operable by the movement of one of said elements, a second contact, means for moving one of said elements into sufllcient proximity to the other element so that the magnetic attraction between the elements will move the yieldably mounted contact into operable engagement with the second contact, and means for adiustably rotating one 01 the magnetic elements, whereby the distance between the magnetic elements will cause a greater or lesser attraction between said elements.

6. In a magnetically operated switch as defined in claim 5 and wherein the means for rotating one of the magnetic elements has associated therewith an adjustment-indicating means.

GEORGE W. CRISE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,171,955 Honeywell Feb. 15, 1918 1,971,035 Fulton Aug. 21, 1934 2,147,604 Kriechbaum Feb. 14, 1939 FOREIGN PATENTS Number Country Date 545,818 Great Britain June 15, 1942 698,016 Germany Oct. 30, 1940 

